Thread testing device



Jan. 3, 1939. 'r. J. NUNAN THREAD TESTING DEVICE Filed larch 5, 1935 15 Sheets-Sheet l INVENTOR. W M

ATTORNEYi Jan. 3, 1939. T. J. NUNAN THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 2 J HQINVENTOR.

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Jan. 3, 1939. T. J. NUNAN 2,142,251

THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 3 INVENTOR.

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1939- T. J. NUNAN 2,142,251

THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 4 l NVENTOR.

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THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 5 1 15 1 1o 1 l3 1 l0 1 19 1 l2 1 8 1 13 1 l1 1 6 ATTORNEY-5.

Jan. 3, 1939. J NUNAN 2,142,251

THREAD TEST ING DEVI CE Filed March 5, 1955 15 Sheets-Sheet e a k i fi L Q g I a u' fmriii Z g INVENTOR.

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ATTORNEYS.

Jan. 3, 1939. T. J. NUNAN 2,142,251

THREAD TESTING DEVICE Filed March 5, 1955 15 Sheets-Sheet 7 INVENTOR.

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Jan. 3, 1939. T. J. NUNAN THREAD TESTING DEVICE Filed March 5, 1955 15 Sheets-Sheet 8 INVENTOR.

Jan. 3, 1939. T. J. NUNAN 2,142,251

THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 9 INVENTOR.

A RNEYJ.

Jan. 3, 1939. T. J. NUNAN 2,142,251

THREAD TESTING DEVICE Filed larch s, 1935 15 Sheets-Sheet 10 INVENTOR- ATTORNEY) Jan. 3, 1939. 'r. J. NUNAN THREAD TESTING DEVICE Filed larch 5, 1935 15 Sheets-Sheet 12 INVENTOR.

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INVENTOR W w I.. MK Kk x in! ski u v65 Jan. 3, 1939. T. J. NUNAN THREAD TESTING DEVICE Filed March 5, 1935 15 Sheets-Sheet 15 INVENTOR. W M BY 4 w %w A'ITO NEYJ.

Patented Jan. 3, 1939 2,142,251

UNITED STATES PATENT- OFFiCE THREAD TESTING DEVICE Thomas J. Nunan, Summit, N. J., assignor to The Clark Thread Company, Newark, N. J., a corporation of New Jersey Application March 5, 1935, Serial No. 9,428

28 Claims. (Ci. 73-51) This invention relates to a novel and improved Fig. 15 but showing a different form of operating form of thread testing device. One of the prinmechanism for the recorder; cipal objects of the invention is to provide a Fig. 18 is a view of the structure of Fig. 17 as device of this character which shall accurately seen from the left of that figure;

make the desired measurements and record Fig. 19 is a top view of the structure appearing 5 them. The novel features making possible this in Fig. 18; object and other objects will be better under- Figs. 20-A and 20-3 together form a wiring stood from the following description and the andiagram illustrating one means by which the nexed drawings, in which I have shown selected device may operate;

1o embodiments of the invention and in which:- Fig. 21 is a view corresponding generally to Fig. 1 is a vertical face view of one of the Fig. 4 but showing different embodiments of selected embodiments; certain parts of the invention;

Fig. 2 is a view on an enlarged scale taken on Fig. 22 is a view substantially on the line the same plane as Fig. 1 and showing more of 22-22 of Fig. 21, parts being shown in section; the details of construction; Figs. 22-A and 22-3 are diagrams showing 1 Fig. 3 is a sectional view taken approximately certain of the parts shown in Fig. 22 but in difon the line 3-3 of Fig. 2; ferent positions;

Fig. 4 is a view on an enlarged scale likewise Fig. 23 is a detail sectional view approximately taken on the same plane as Fig. 1 but with ceron the line 23-23 of Fig. 21; tain parts removed so as to show details of con- Fig. 24 is a wiring diagram illustrating the 80 truction; operation of the embodiment shown in Figs. 21,

Fig. 5 is a view taken from the right of Fig. 4 22, 22-A, 22-13, and 23, and showing how that showing the structure appearing in that figure, embodiment can be used in connection with the parts here also being broken away, better to show wiring diagram of Figs. 20-A and 20-13;

25 certain details; Fig. 25 is a wiring diagram of another manner 35 Fig. 6 is a view taken approximately on the line of operating the device and which may be used 6-6 of Fig. 3, but with the back of the casing in place of the wiring diagram of Figs. 20-A removed and with parts being broken away to and 20-3;

show details of construction; Fig. 26 is an end view of a recorder which may Fig. 7 is a partly sectional view on an enlarged be used with the wiring diagram of Fig. 25; 30 scale taken approximately on the line i-i of Fig. 27 is a view of the face of the recorder, Fig. 5; this view being taken on the line 21-21 of Fig.

Fig. 8 is a section approximately on the line 26; 8-8 of Fig. '7; Fig. 28 is a view looking in the same direction Fig. 9 is a view approximately on the line 9-9 as Fig. 27 but with the front or top cover or panel 35 of Fig. 8; of the cabinet removed;

Fig. 10 is a view also on an enlarged scale taken Fig. 29 is a sectional view on a greatly enlarged approximately on theline Ill-i0 of Fig. 2; scale approximately on the line 29-29 of Fig. 27; Fig. 11 is a view on an enlarged scale taken Fig. 30 is a view substantially on the line approximately on the line Il-ll of Fig.2; 30-30 of Fig. 29, which is also approximately 4 Fig. 12 is a fragmentary view corresponding to the plane upon which Fig. 28 is taken; Fig. 1, but showing certain of the parts in difier- Fig. 31 is a view showing the construction of ent positions; one of the rotary switches which appear in the Fig. 13 is a view of a fragmentary portion of various wiring diagrams; Fig. 12 illustrating the operation of the parts Fig. 32 is a view of the switch appearing in 46 shown therein; Fig. 31 as seen from the right of that figure.

Fig. 14 is a face view of a fragment of the rec- I have shown the invention as embodied in a ord strip printed by operation of the device; device for testing thread to the br aking point.

Fig. 15 is a side elevation, partly in section, although certain features of the invention may 50 of a recorder and the operating mechanism be found to have application to other uses, I 50 therefor; shall first describe the operation of the device Fi 16 i plan view of the structure appearand then elaborate on various details thereof. ing in Fig. 15 but with the casing top removed Referring first to Fig. 1, I have shown therein and certain parts shown in section; a thread cylinder I forming a source of supply Fig. 17 is a view taken on the same plane as for thread to be tested and from which the II 8. The scale is selected as a suitable form of indicator or measuring instrument and may be of any of the well-known forms which may be found suitable for the purpose. Therefore the details of the scale mechanism will not be described except as they are. of interest in understanding the invention. The indicating part of the measuring instrument may be omitted entirely for some purposes, and therefore the word indicator is used merely for convenience of expression.

For the purpose of convenience I shall refer to the clamp 5 as the indicator clamp, since it moves with the indicator.

The frame 4 is rotatably mounted about its axis 9 on a suitable support I0, here shown in the form of a panel extending upwardly from a base I, and is operated in a clockwise direction, as viewed in Fig. l. The operating means will be more fully described presently.

Rotatably mounted upon the panel i0 is a rock shaft l2 having on the front of the panel a lever l3 secured thereto, and upon the outer end of this lever is a clamp M which, for the sake of convenience, I shall refer to as the breaking clamp. As best shown in Figs. 2 and 6, on the back of the panel In the rock shaft i2 has an arm l5 which is urged towards the base it by means of a spring i6. 4

By means to be described later, the clamps 5 and M are periodically operated in synchronism with the movement of the lever l3 and the frame 4. The frame 4, as indicated, comprises a plurality of arms, here shown as four in number and which I have designated as l7, l8, l9, and 20, and is given an intermittent rotation in the direction indicated by the arrows in Figs. 1, 2, and 12.

On the end of each of the arms l I, H8, H9, and 20 is a feed clamp, the construction of which is best shown in Fig. 10. Here the clamp is shown as formed of two jaws, one jaw 2| being stationary and secured to the end of a horizontally extending tubular finger 22. The other jaw 23 is movable and is mounted upon a plunger 24 slidably mounted in the tubular finger 22 and normally urged towards the left of Fig. 10 by means of a light spring 25 which engages between the end of the tubular finger and an abutment on the plunger.

The strength of the spring 25 is such that the jaws 2| and 23 will yieldingly clamp a thread between them with sufficient force to pull the thread from the source of supply L It will be seen that the jaws flare outwardly from each other towards their peripheries in order to receive the thread and also in order to permit forcing of the jaws apart at certain points. This forcing apart may be done by a release member 26 or 21 (Figs. 1 and 2) of identical construction, and details of which are better shown in Figs. 7 and 10. It will be seen that each release member comprises a wedge 28 slidably mounted on a block 29 secured to the panel l0 and held in adjusted position by means of a screw 30 received in a slot 3|. The wedge moves in suitable guideways on the block, as indicated.

The intermittent motion of the frame may be caused by any suitable means, here exemplified by a Geneva cross 32 mounted upon the shaft 9 on the back of the panel I0 and operated by a pin 33 on an arm 34 secured to a shaft 35. Associated with the arm 34 is the usual disk 35 engaging the arcuate portions of the cross to hold it against movement when the pin 33 is not operating. Of course, other suitable types of intermittent movements may be used.

The shaft 35 is rotated from'a motor 31 which, through a gearing train contained in a gear box 38, rotates a pinion 39 meshing with a gear 45 se-' cured to the shaft 35. The shaft 35 forms a cam shaft extending through the panel III in which it is supported by suitable bearings, and on the front end thereof it carries a cam 4| engaging a cam roller 42 upon the lever I3.

Assuming that the parts are in the positions shown in Figs. 1 and 2, the thread is carried from the source of supply I through the tension device 3 over the clamps on the arms l9 and I3 and through the clamps 5 and I4. The clamp on the arm l9 will be closed so that the thread will run freely over that clamp, the jaws thereof forming a guide for the thread. The jaws of the clamp on the arm l8 will beheld open by the release member 25 so that while the thread may still run freely between those jaws, nevertheless when the jaws are closed the thread will be held therebetween.

The end of the thread below the clamp l4 will be inserted between the jaws of the clamp on the arm ll so as to be held to that arm.

The motor 31 can now be put in operation and the shaft 35 will be rotated, causing the cam 4| to rotate in a counterclockwise direction as seen in Figs. 1, 2, and 12, and depress the lever l3. As the lever i3 moves downwardly, it will carry with it the clamp I4 and the thread held therein. The thread will exert a tension upon the clamp 5 and thus upon the bracket 6, and will actuate the indicator exemplified by the scale. The cam 4| is so designed as to insure that the thread will break between the clamps 5 and i4 while the frame 4 is still stationary and before the pin 33 engages the Geneva cross. The approximate positions which the parts will now occupy are indicated in Fig. 12.

After the thread is thus broken, the frame will be rotated by the intermittent movement, it being noted that the arm 34 and cam 4| are so positioned on the cam shaft 35 that the frame is held stationary during depression of the lever l3 by the cam 4|. The clamps 5 and H are released by means to be described later, and then the frame 4 will be rotated in the direction of the arrows indicated in Figs. 1 and 2. This rotation of the frame will cause the feed clamp on the end of the arm l8 to move away from the rearm l9 will occupy the position shown as occupied by the arm l8, and as it reaches that position, the feed clamp on the end thereof will be opened by the release 25. The arm ID with the thread secured thereto will have moved down to the position shown as occupied by the arm l1, and it will thus be seen that the thread is carried through the jaws of the clamps 5 and M by a single feed clamp on the end of one of the trode arrangement for a cathode ray commutator in which a larger power than that given by the arrangement of Fig. 2 can be obtained. 9

In Fig. 4, a cathode ray tube has a first cathode 39 which is in the form of a short filament running at right angles to the plane of the paper. This cathode is heated by current from a battery 99. Next to the cathode 38 is a modulating grid 91 and then a magnetic focusing coil 99, which is designed to project a line image of the cathode on the grid 99, in close proximity to which is placed a collecting electrode 94. The arrangement and function of this part of the apparatus will be described more fully later. A pair of defleeting plates 49, 4|, are provided for deflecting the electron beam from the cathode 95 over the grid 99. A second cathode 42 is arranged on the side of the grid 99 nearest the cathode 95, and to one side of the path of the electrons from the first cathode 95, so that these electrons pass it, and fall on one side of the grid 39. The cathode 42 is heated by a battery 49. On the side of the grid 99 remote from the cathodes is placed a modulating grid 49, then a magnetic focusing coil 44, and finally a contact assembly 45, the contacts on which may be connected by wires to the electrodes of the cell, as described with reference to Figs. 1 and 2, or may be attached to the cell as described with reference to Fig. 3.

The construction of the grid 99 and the relative positions of this grid, the electrode 94 and the cathode 42 are shown in Figs. 5 and 6. The grid 99 comprises two supporting uprights 58 and 51, the upright 51 being made of, or being coated with a layer of resistive material. The connection to the outside of the tube is made by a metal conducting strip 59. The grid consists of a number of small grids 59 arranged side by side spaced apart from one another, and connected to the resistive element 51. The number of grids 59 is made equal to the number of elements it is desired to reproduce in a picture line, that is equal to the number of crystals of the modulating cell 4 of Fig. 1. The position of the cathode 42 relative to the grid 99 is shown in dotted lines in Fig. 5, and as a full line in Fig. 6, and the beam from the cathode 95 falls on the grids 59 on that part of them which is between the cathode 42 and the support 59. The electrode 94 consists of two plates (which are suitably connected together electrically) arranged one on each side of the beam from the cathode 35, and held at a high potential relative to the grid 39, which is biassed negatively relatively to the cathode 42. The connections of these electrodes to the battery 55 are shown in Fig. 4. Preferably a shielding electrode 90 connected to the cathode 42 is provided between the latter and the collecting electrode 34. The bias on the grid 99 is such that no emission from the cathode 42 passes it.

The operation of the cathode ray tube is as follows. Television signals received by the aerial 41 are amplified by an amplifier 49, and applied to a separating arrangement 49 which separates the picture signals, line synchronising signals and frame synchronising signals from each other. The frame synchronising signals appear at 60 and are used to control the slow speed scanner 1 of Fig. 1. The line synchronising signals appearing at 5| are fed to a time base circuit 52 to control the generation of saw tooth impulses at line frequency which are fed to the deflecting plates 49, 4|. The picture signals appear at 59 and are fed through a condenser 54 to the modulating ranged by suitably choosing the potential difference between the cathode 9i and grid 39, and

by making that part of the grid 59 of suitable material (e. g. by coating it with a substance which readily emits secondary electrons) that the number of secondary electrons emitted exceeds the incident electrons. There will be produced on the grid E9 in question a positive charge proportional to the strength of the beam falling thereon, which is in turn proportional to the brightness of the corresponding picture element.

The resulting decrease in negative bias of the grid 59 will result in a flow of electrons from the cathode 42 through the grid 59. This electron current passes through the grid 43 (Fig. 4) on which is impressed a high frequency oscillation of the frequency required for driving the crystals of the light modulating device. This frequency is generated by an oscillator 9| and fed to the grid 49 through a transformer 92. The focussing coil focusses an electron image of the grid 99 on to the contact assembly 45, the image of each grid 89 in the grid 99 being imaged on one contact. Thus each contact will have falling on it a beam of electrons which is modulated in amplitude by the picture signal corresponding to it and by the high frequency oscillation from the generator 9|. and a corresponding train of waves will be set up in the cell and used as described with reference to Fig. 1. When the beam from the cathode moves of! one grid 59 on to the next one, the charge on the first grid will begin to leak away through the resistive support 51, the resistance being such that the charge received from the beam from the cathode 35 has substantially entirely leaked away within one line period. It will be seen that'the above apparatus provides a certain storage eflect since a modulated oscillation continues to be applied to each contact after the beam has moved away from the corresponding grid, dlle to thetime required for the charge to leak away from the grid.

It has been observed that if a quartz piezoelectric crystal has only a part of its surface covered with the electrodes, and an oscillation is applied thereto, only the part of the crystal covered with the electrodes will vibrate, the remainder being unaffected.

The present invention therefore provides a modification of the arrangements previously described, in which the crystal assembly is replaced by a single crystal extending over the whole length of the cell. In one example, illustrated in Fig. 7, the crystal 89 is covered on the side remote from the liquid by a number of separate electrodes 9|. These electrodes may be formed of fine wires, and the spaces between them may be filled with an insulating material. On the other side of the crystal 9!! is fixed a common electrode 92, for example a steel plate.

In an alternative arrangement using the above stated fact, the crystal surface is itself exposed to the cathode ray beam in place of the capacity connection shown in Fig. 3. In this case the focussing system of the tube, which may be a cylindrical focussing system, preferably causes the beam to fall on a narrow strip of the crystal taken at right angles to the longer dimension of the latter.

In any of the embodiments of the invention described above, the distance between the crystal or crystals and the opposite wall of the cell can be made such that the wave reflected from this wall produces standing waves with the Waves from the crystal. By utilising the reflection of the waves to and fro across the cell, the effect of the waves may be made'to persist for some time after the scanning cathode ray beam has passed on to another partof the crystal or crystal assembly, thereby giving an enhancement of the light passing through to the screen.

The cell wall may be fitted with'a special refleeting surface as shown in Fig. 8. The reflector can be made from, for example, a polished plane metal surface 83, which may be of stainless steel. The distance of the reflector from the crystals 86 is made very short to achieve a multiple reflection. In this way, the short excitation of the supersonic waves in the liquid is prolonged for the whole duration time of a line. It is also an advantage to apply only a low damping to the crystal to obtain in this way a persistence of the oscillations, for example by exciting it with a frequency which is a harmonic of the natural frequency of oscillation of the crystal itself. The width of the resonance band may be, for instance 100 kilocycles instead of the usual 2 megacycles.

It will be noticed that in any arrangement of the present invention the waves are not travelling along the cell parallel to the direction of line scanning as in the case of the device according to British Patent specification No. 439,236. In that arrangement, owing to the necessity for the light beam to be parallel in the direction of movement of the waves, the major restriction of the size of the light source and its aperture is in the line scanning direction. In the present invention there is no restriction in this direction, with consequent increase in light. The only restriction is in the direction at right angles to this, where in both cases there is a restriction owing to the necessity of forming a narrow image on the screen, and owing to the necessity for keeping the width of the low speed scanning member reasonably small. For example, the present invention makes it possible to use a cinema arc lamp with a large arc crater, and full use of the light available from which such a source can be made.

The piezo-electric crystal assembly may be I made from a large number of small crystals stuck on a steel plate, acting as one electrode, and having on the other side the separate electrodes for the generation of the separate wave-trains. Such an assembly acts in a similar way to the arrangements previously described.

I claim:

1. A television receiver comprising, in combination, a cathode ray tube having an electron gun for producing a beam of electrons and an electrode system for modulating said beam with received picture signals and with a high frequency electrical oscillation, a light modulating device of the kind utilising the diffraction effect on light of high frequency mechanical waves in a liquid medium, said light modulating device comprising a plurality of generators equal in number to the number of elemental areas in the picture line for generating a plurality of parallel trains of high frequency mechanical waves in said liquid medium, said light modulating device being arranged in the path of said beam 'of electrons so that said beam scans said genand an optical system for forming an optical dlffraction image of said trains of waves to reconstitute a picture line on a receiving screen, and frame scanning means for sweeping said image over said screen.

2. A television receiver according to claim 1 wherein said generators comprise a piezo-electric crystal assembly having a plurality of electrodes arranged on the side thereof remote from said liquid medium a plurality of contacts arranged within said cathode ray tube and in close proximity to said electrodes, whereby voltages induced on said contacts by said beam of electrons are transmitted to said electrodes by virtue of the capacity existingbetween said contacts and said electrodes.

3. In combination in a television receiver, means for producing a picture line comprising a supersonic wave light modulating device in which there are provided a plurality of generators of mechanical waves equal in number to the number of elements it is desired to reproduce in a line of the received picture, cathode ray tube commutating means for relegating to each generator a high frequency oscillation modulated with that part of the picture signal in each line apportionate thereto, and an optical system for producing from light diffracted by said trains of waves a picture line on a screen.

4. A television receiver comprising a light modulating device of the kind utilizing the diffraction effect on light of high frequency mechanical waves in a liquid medium and comprising a plurality of similar generators for generating a plurality of trains of high frequency mechanical waves in said liquid medium, each train corresponding to an elemental picture area of a picture line, electronic line-scanning means for exciting said generators one after the other with an electron stream modulated in intensity in accordance with received picture signals and interrupted at a high frequency suitable for exciting said generators, optical means for forming an optical diffraction image of said trains of waves on a receiving screen, and mechanical frame scanning means for sweeping said image in a direction at right angles to its length over said screen to produce the frame scanning component and thus reconstitute a received picture.

5. A television receiver comprising a light modulating device of the kind utilizing the diffraction effect on light of high frequency mechanical waves in a liquid medium and comprising a plurality of similar generators for generating a plurality of trains of high frequency mechanical waves in said liquid medium, each train corresponding to an elemental picture area of a picture line, a cathode ray tube having an electron gun for producing a beam of electrons, means for modulating said beam with received picture signals and also with high frequency suitable for exciting said generators, a plurality of contacts, each of said contacts being associated with one of the said generators through an alternating current path, and means for deflecting said modulated beam of electrons over said contacts at line frequency, optical means for forming an optical diffraction image of said trains of waves on a receiving screen, and mechanical frame scanning means for sweeping said image in a direction at right angles to its length over said screen to produce the frame Electric current may be supplied to the device from any suitable source, here indicated in Fig. 20-8 as two line conductors I38 and I09 carrying a 110 volt, 60 cycle, alternating current. The conductors I08 and I39 lead to the opposite sides of the motor 31, the conductor I98 having therein a switch IIO operated by a solenoid III, the switch and solenoid together forming what for convenience may be referred to as the "trip relay". The function of this trip relay will be more fully discussed later.

The solenoids 63 are connected by conductors H2 and H3 to the conductors I08 and I09, respectively, and lead through the primary of a transformer II4, the secondary of which is connected through a rectifier II5 with the solenoids 63, these solenoids being arranged in parallel with each other through variable resistances, if such are desired. The purpose of the rectifier is to provide a one-way current through the solenoids, as will be apparent to those skilled in the art.

In the conductor H2 is shown the cam-operated switch 95, which switch thus controls the operation of the solenoids, and it will be seen that thisoperation is also controlled by'means of the "breaker switch I03 shown as located in the conductor I09.

The lamp 14 is likewise connected, by means of the conductors H8 and I I1, to the conductors I08 and I09 and lead therefrom to'the primary of a transformer II8, the secondary of which is connected to the lamp 14 by the conductors H9 and I20. It will be seen that the cut-oif switch 99 shown located on the scale in Fig. 5 is indicated in the conductor H9, and therefore this switch controls the operation of the lamp.

Likewise connected to the conductors I08 and I09 is the photo-electric cell 13. This connection may be made by the conductor I connected to the conductor H8 and thus to the conductor I08, the conductor I2I leading to the amplifier I22. This amplifier is of known construction, and one form which I have found suitable for the present purpose is sold under the name of Westinghouse type .LE amplifier. The other line conductor I09 may be connected to the other side of the amplifier I22 by means of the conductor I23. From the amplifier I22 lead two input leads I24 and I25 to opposite sides of the cell 13. The recorder switch I84 is shown as being located in the conductor I23 and thus this switch controls the amplifier and through the amplifier controls the operation of the photo-electric cell, as well as of other elements to be described later.

The ratchet solenoid may be connected through the conductor H6 connected to one of the line conductors I83, part of the conductor I2 I, conductor I25 switch I21, conductor I28, rectifier I29, conductor I30, to one side of the solenoid. Theother side of the solenoid 10 may be connected to the line conductor I39 through the conductor I3I, rectifier I29, switch I04, and conductor I23. It will be noted that the switch 96 is located in the conductor I3I.

It will thus be seen that the ratchet solenoid, photo-electric cell, lamp, motor, and clamp solenoids are all connected across the line formed by the conductors I08 and I09.

By the conductors H6, I2I, I28, I28, I23, and switch I04, the rectifier I29 is likewise connected across the same line. This rectifier has the function, known in the art, of giving the effect of a one-way current, and in the arrangement switches illustrated it is used to supply current to substantially all the recording apparatus.

Current through the rectifier, and consequently through the recording apparatus, is controlled by the recorder switch I04 and also by the switch I21, which in turn is controlled by the solenoid I32, this switch and solenoid forming the dash-pot relay or other time-delay relay.

The various relay switches and magnet-operated switches indicated are supplied with the usual springs tending to keep them open or closed, as the case may be.

Connected to the amplifier I22 and receiving an amplified current therefrom is a circuit including the conductors I33 and I34 connected to opposite sides of the magnet I35 controlling I36 and switches together being constructed so as to be a quick-acting relay.

The switch I36 is in a circuit leading from one side of the rectifier I29 through the conductors I38 and I39 to one side of the switch, the conductor I40 leading from the switch to the magnet I4I forming part of a rotary switch I42, and the conductors I43 and I44 leading to the other side of the rectifier I29. 7

The rotary switch I42 will hereinafter be referred to for convenience as rotary switch No. 1. This switch and other rotary switches hereinafter referred to may be of the type shown in Figs. 31 and 32, and the construction of which will be more fully described later.

For the present it is sufficient to say that the switch I42 comprises a rotary shaft I45 upon which are secured the three wiping contacts or brushes I46, I41, and I48. In the diagram of Fig. 20-3, these three contacts are shown on separate centers but are connected together. by dotted lines, to show that the centers are preferably coincident in practice. The wiping contact I46 wipes over homing contacts I49, while the wiping contacts I41 and I48 wipe over selector contacts I50 and I5I, respectively.

The circuit closed by engagement of the wiping contact I46 with one of the contacts I49 includes the switch I52 operated by the magnet I4I, the contacts I46 and I49, the conductor I53,

the normally-closed switch I54, conductors I55,,

I56, and I38, leading to one side of the rectifier, while the other side of the rectifier is connected through the conductors I44 and I43 and magnet I to the switch I52.

The circuits closed by engagement of the wiping contacts I41 and I48 with the contacts I50 and I5I, respectively, will be described later, as these circuits include apparatus which has not yet been described.

There is shown a plurality of relays referred to, respectively, as slow release relay No. 1, slow release relay No. 2, vibrating reed relay, slow release relay No. 3, and slow release relay No. 4. The circuits for these relays will now be described.

The magnet I51 operating the normally-open switch I51 of slow release relay No. 1, has current supplied to it on one side thereof by a conductor I58 leading through the switch I31 and the conductors I39 and I38 to one side of the rectifier I29, to the other side of which the magnet I56 is connected by means of conductors I44 and I43.

One side of the normally-open switch I51 is connected to one side of the rectifier I29 by means of the conductors I44, I43, and I59, while the other side of the switch I51 is connected to I31, this magnet and the 

